Liquid ring machines are generally described in DE-A-43 05 424, which corresponds to U.S. application Ser. No. 08/505,228, the text of which is hereby incorporated by reference. In liquid ring machines, the position of the rotor relative to the inside contour of the machine housing has an effect on machine performance. Depending upon the circumferential velocity of the rotor, the pressure ratio of the machine, or its demand for working liquid, various installation positions of the rotor can result in better or worse machine performance. Further variations in machine performance may arise from dimensional tolerances present in the production technologies employed for their manufacture.